I've had a fine gaming experience with a Radeon HD 5470 mobility 512mb graphics card. It plays all of your games like Portal 2, the Half Life series, every older title you can think of on medium - high details. It can cope well with quite a few new games too on low - medium.
I even managed to get a stuffty but playable FPS with GTA IV and have worked through a good portion of the game.
For a card that is well past its prime and on a laptop, I think it does really well. Shaderless Minecraft is flawless, and shaderless / low setting shaders in Blockland is very good as well.
The technology behind the card is dated and it isn't particularly fast so its dragging behind a good lot now in terms of usefulness. But still, not bad at all having used it in the last couple of years.
I don't understand why people buy the most expensive card they can find. They often say they do it to "future proof" but the technology behind graphics cards changes and you'll fall out of date in other ways over time. If you spend less money on a still decent card, you can upgrade it in the next two to three years when you'd probably want to anyway.